Hydroxyapatite, Ca 5 OH(PO 4 ) 3 , is a mineral found in teeth. In hydroxyapatit

Question

Hydroxyapatite, Ca5OH(PO4)3, is a mineral found in teeth. In hydroxyapatite, there are:

Blank 1 atoms of Ca
Blank 2 atoms of H
Blank 3 atoms of O
Blank 4 atoms of P, and
has a molar mass of Blank 5 (report a whole number)

In gas law probems, we define Standard Temperature and Pressure as

The molar mass of strontium carbonate, SrCO3, is 147.6 g/mole. How many moles are in 12.60 g of magnesium carbonate?

Mg +  Blank 2 O2   ?    Blank 3 MgO

KClO3   ?   Blank 2 KCl  +  Blank 3 O2

AgNO3 +  Blank 2 H2S    ?    Blank 3 Ag2S +  Blank 4 HNO3

N2 +  Blank 2 H2    ?    Blank 3 NH3

C7H16 +  Blank 2 O2    ?    Blank 3 CO2 +  Blank 4 H2O

In preparation for an experiment you calculate that 60 g of product should be produced. You do the experiment and actually produce 33 g. What is the percent yield?

The first step in the production of nitric acid from ammonia and oxygen is
                                                              4 NH3 + 5 O2    ?    4 NO + 6 H2O.
How many grams of O2 are required to product 90 g of NO?

What is the pressure in a 1.2 L vessel containing 0.32 moles of O2 if the temperature is 23oC? (R, the universal gas constant, is 0.082 L atm / mole K.)

The amount of energy required to raise the temperature of 1 gram of a substance by 1oC is called its

What is the molarity of a solution prepared by dissolving 8.67 g of potassium iodide, KI, in 250 mL of water? (The molar mass of KI is 166 g/mol.)

Explanation / Answer

blank 1: 5

blank 2: 1

blank 3: 13

blank 4: 3

blank 5: 502.31 g (add up the weights of all atoms)

Standard temperature is 25C, or 298K

Standard pressure is 1 atm, or 101325 Pa

Magnesium Carbonate weighs 84.3139 g per mole. So, 12.60 / 84.3139 = 0.149 mol

2 Mg + O2 = 2 MgO (balanced)

2 KClO3 = 2 KCl + 3 O2 (balanced)

2 AgNO3 + H2S = Ag2S + 2 HNO3 (balanced)

N2 + 3 H2 = 2 NH3 (balanced)

C7H16 + 15 O2 = 7 CO2 + 16 H2O (balanced)

33g / 60g = 0.55 *100% = 55% yield

Ammonia is converted to nitric acid in 2 stages. It is oxidized (in a sense "burnt") by heating with oxygen in the presence of a catalyst such as platinum with 10% rhodium, to form nitric oxide and water.

We see that O2 is in a 5:4 ratio with NO. So if we need 90 grams of NO, then we can convert that to moles by dividing by formula weight 30, which gives us 3 moles produced. 3.75 moles of O2 is needed(this fits the 5:4 ratio), which would be 3.75 mol * 32g = 120g of O2 needed

p=nRT / V
p= (0.32)(0.082)(296K) / (1.2)
p=6.5 atm

specific heat

molarity = mols / vol L
molarity = (8.67g / 166 g) / .250 L

molarity = 0.2089 or 0.21M

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